There is a growing need for the synthesis of chiral compounds which are used as pharmaceuticals and agrochemicals. Classical methods of separation of the optical isomers are one aspect of the synthesis, which result in the cumbersome process of resolution and racemization, often making the process uneconomical. Another way of preparing the chiral compound is to use chiral synthesis approach which is being increasingly used as preferred industrial method. This synthesis involves the use of chiral reagents, and especially use of chiral catalysts to bring about the desired transformation.
Various catalytic systems have been used for different types of chiral transformations. Some of these systems use bidentate organophosphorous compounds which have attained great importance as ligands in homogeneous catalysis. Hydroxyphosphine compounds of Formula IA are useful as ligands on transition metals in metal catalyzed asymmetric reactions such as hydrogenation, hydroformylation, rearrangement, allylic alkylation, cyclopropanation, hydrosilylation, hydride transfers, hydroborations, hydrocyanations, hydroxycarboxylations, and so on (ref. US 2006/0089469 A1).

US 2006/0089469 discloses compound of Formula IA and the process of making the same.
WO 2009136409 discloses a process for the asymmetric hydrogenation of a prochiral ketimine to get a chiral amine wherein the said transformation is effectively carried out in the presence of iridium and rhodium complexes containing the ligand of Formula IA, which upon reaction with haloacetyl chloride affords various haloacetanilide herbicides. In particular, the preferred ligand is [(1R,2R,3S)-1,2-dimethyl-2,3-bis(diphenyl phosphine methyl) cyclopentyl]methanol (herein after referred to as compound of Formula A). However, this publication does not teach an industrially feasible route for the synthesis of said compound of formula A.

WO 2008092924 discloses a process for selectively synthesizing a stereoisomer of zilpaterol by reacting 4,5-dihydro-imidazo[4,5,1-jk][1]benazepine-2,6,7[1H]-trion-6-oxime with H2 in the presence of a catalyst to selectively form a stereoisomer of 6-amino-7-hydroxy-4,5,6,7-tetrahydroimidazo[4,5,1-kj][1]-bencazepin-2[1H]-one, which, in turn is converted to zilpaterol or a salt thereof. The catalyst used in the reaction comprises metal complex of a ligand with a metal from transition group VIII. One such ligand used is ligand of Formula A.
These highly useful bidentate ligands of Formula A can be prepared by the process disclosed in US 2006/0089469. Schematic diagram of the process is shown below in Scheme I.

In the above reaction scheme, the group OPG- represents a hydroxyl protecting group. Komarov et al. in Tetrahedron Asymmetry, 13 (2002), 1615-1620 have disclosed a scheme to prepare the said ligand. Scheme II represents the scheme to prepare the said hydroxyphosphine ligand.

Inventors of the present invention, in an effort to prepare the hydroxyphosphine ligand of Formula A, tried to follow the process mentioned above. However, even after a series of experiments, the desired ligand could not be prepared in desired and reported yield. In fact, the yield was always negligible and the results were not reproducible. Working in a persuasive manner, the inventors of the present invention prepared novel intermediates which can be easily and conveniently converted into hydroxyphosphine ligands having application as mentioned above.
Accordingly, the present invention provides novel intermediates of Formula I useful in the preparation of hydroxyphosphine ligands useful in metal catalyzed asymmetric synthesis.
Further, according to the authors of Komarov et al. and US'469, the diol intermediate is selectively protected by converting it into tosylate (i). The publication also mentions that the more hindered hydroxyl group had to be protected before it could be reacted with lithium diphenylphosphine to avoid undesired cyclization.
Both the prior art references mentioned above use the route which involves selective protection of the less hindered alcohol group to get intermediate (i) which is difficult to handle as it has a tendency to undergo cyclization to form the compound (ii). Formation of compound (i) is very tricky as it is already known that while trying to form monotosylate (i) from the diol (x), the ditosylate (iii) also forms (Advances in catalysis, vol. 25, p 81-124, 1976). The monotosylate (i) and the ditosylate (ii) have to be separated by column chromatography. According to the reference, the monotosylate is used immediately after separation.

Formation of compound (i) is carried out under dry conditions, and uses large volume of pyridine as a solvent, which is carcinogenic, and is not an environmentally friendly solvent. Pyridine also makes the process less cost effective. Since it is soluble in water, its recovery is very difficult and need extra efforts. The reference does not mention any usefulness of the compound (ii), and is an unwanted product for the process.
Asymmetric homogenous hydrogenation, J D Morrison, W F Masler, M K Neuberg, Advances in Catalysis, Vol 25, pp. 81-124, [1976], also discloses a survey of asymmetric homogenous hydrogenation reactions, that is reactions that create asymmetric carbon atoms by the addition of hydrogen across multiple bonds under the influence of soluble chiral catalysts. This publication teaches a process for the preparation of Camphos from commercially available (+)-camphoric acid.

In the paragraph bridging pages 98-99, this publication teaches that in the initial trials to synthesize camphos, many procedures were used in an attempt to prepare dihalide from the diol. However, none of a great many standard methods met with any success. The procedures tried involved thionyl chloride, pyridine, phosphorus pentachloride and triphenylphosphine dibromide in N,N-dimethylformamide, triphenylphosphine and carbon tetrachloride, tris(dimethylamino)phosphine and bromine, o-phenylenephosphorochloridite and bromine, tris(dimethylamino)phosphine and carbon tetrachloride and tri-n-octylphosphine and carbon tetrachloride. This publication further states in the last paragraph on page 99 that the synthesis of camphos by displacement on its ditosylate precursor with the diphenylphosphide anion appeared promising on paper, but initially was a dismal failure in practice. It was considered likely that the less hindered α-tosylate group was displaced or eliminated rather readily at room temperature but the neopentyl-like-β-tosylate group required more strenuous conditions to effect its displacement. This was also found to reduce the yield of the target hydroxydiphosphine ligand, which is clearly undesirable.
Accordingly, there is a need in the art for a process for the preparation of a compound of formula A conveniently, in high yield and preferably, without utilizing an intermediate compound having a tosylate leaving group.
In fact, attempts to prepare the desired compound of formula A using the conventionally known process led to the undesired yield of an oxidized product only instead of the desired compound of formula A, having the formula set out below:

Inventors of the present invention, in an effort to prepare the hydroxyphosphine ligand of Formula A, tried to follow the process mentioned above. However, even after a series of experiments, they could not form (i) in desired and reported yield. In fact, the yield was always negligible and the results were not reproducible. Working in a persuasive manner, the inventors accidently found that the compound (ii) which was considered to be unwanted product by the prior art reference, can be conveniently and effectively converted into the desired hydroxydiphosphine ligand of Formula A.
Thus, there is a need in the art for a process for preparing hydroxydiphosphine ligands in high yield. These hydroxydiphosphine ligands are suitable precatalysts for the enantioselective manufacture of optically active agrochemicals, particularly chloroacetanilide herbicides. The process of the present invention is cost effective, environmentally friendly, simple, and reproducible.